RTC: add DT bindings to pxa-rtc

This patch adds generic device tree bindings to the PXA RTC driver.
Documentation for bindings were also added.
Signed-off-by: Daniel Mack <zonque@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>

Documentation/devicetree/bindings/rtc/pxa-rtc.txt

+* PXA RTC
+
+PXA specific RTC driver.
+
+Required properties:
+- compatible : Should be "marvell,pxa-rtc"
+
+Examples:
+
+rtc@40900000 {
+	compatible = "marvell,pxa-rtc";
+	reg = <0x40900000 0x3c>;
+	interrupts = <30 31>;
+};

drivers/rtc/rtc-pxa.c

@@ -27,6 +27,8 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 
 #include <mach/hardware.h>
 
@@ -396,6 +398,14 @@ static int __exit pxa_rtc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_OF
+static struct of_device_id pxa_rtc_dt_ids[] = {
+	{ .compatible = "marvell,pxa-rtc" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pxa_rtc_dt_ids);
+#endif
+
 #ifdef CONFIG_PM
 static int pxa_rtc_suspend(struct device *dev)
 {
@@ -425,6 +435,7 @@ static struct platform_driver pxa_rtc_driver = {
 	.remove		= __exit_p(pxa_rtc_remove),
 	.driver		= {
 		.name	= "pxa-rtc",
+		.of_match_table = of_match_ptr(pxa_rtc_dt_ids),
 #ifdef CONFIG_PM
 		.pm	= &pxa_rtc_pm_ops,
 #endif